Provided by: python3-watchdog_6.0.0-4_all 
NAME
watchdog - watchdog Documentation
Python API library and shell utilities to monitor file system events.
Works on 3.9+.
DIRECTORY MONITORING MADE EASY WITH
• A cross-platform API.
• A shell tool to run commands in response to directory changes.
Get started quickly with a simple example in Quickstart <#quickstart>.
EASY INSTALLATION
You can use pip <https://pypi.python.org/pypi/pip> to install watchdog quickly and easily:
$ python -m pip install -U watchdog
Need more help with installing? See Installation <#installation>.
INSTALLATION
watchdog requires 3.9+ to work. See a list of Dependencies.
Installing from PyPI using pip
$ python -m pip install -U watchdog
# or to install the watchmedo utility:
$ python -m pip install -U 'watchdog[watchmedo]'
Installing from source tarballs
$ wget -c <https://pypi.python.org/packages/source/w/watchdog/watchdog>-5.0.4.tar.gz
$ tar zxvf watchdog-5.0.4.tar.gz
$ cd watchdog-5.0.4
$ python -m pip install -e .
# or to install the watchmedo utility:
$ python -m pip install -e '.[watchmedo]'
Installing from the code repository
$ git clone --recursive git://github.com/gorakhargosh/watchdog.git
$ cd watchdog
$ python -m pip install -e .
# or to install the watchmedo utility:
$ python -m pip install -e '.[watchmedo]'
Dependencies
watchdog depends on many libraries to do its job. The following is a list of dependencies you need based
on the operating system you are using.
┌─────────────────────┬─────────┬───────────┬──────────────┬─────┐
│ Operating system │ Windows │ Linux 2.6 │ macOS Darwin │ BSD │
│ Dependency (row) │ │ │ │ │
├─────────────────────┼─────────┼───────────┼──────────────┼─────┤
│ XCode <https:// │ │ │ Yes │ │
│ developer.apple │ │ │ │ │
│ .com/technologies/ │ │ │ │ │
│ tools/xcode.html> │ │ │ │ │
└─────────────────────┴─────────┴───────────┴──────────────┴─────┘
The following is a list of dependencies you need based on the operating system you are using the
watchmedo utility.
┌─────────────────────┬─────────┬───────────┬──────────────┬─────┐
│ Operating system │ Windows │ Linux 2.6 │ macOS Darwin │ BSD │
│ Dependency (row) │ │ │ │ │
├─────────────────────┼─────────┼───────────┼──────────────┼─────┤
│ PyYAML <https://www │ Yes │ Yes │ Yes │ Yes │
│ .pyyaml.org/> │ │ │ │ │
└─────────────────────┴─────────┴───────────┴──────────────┴─────┘
Supported Platforms (and Caveats)
watchdog uses native APIs as much as possible falling back to polling the disk periodically to compare
directory snapshots only when it cannot use an API natively-provided by the underlying operating system.
The following operating systems are currently supported:
Warning:
Differences between behaviors of these native API are noted below.
Linux 2.6+
Linux kernel version 2.6 and later come with an API called inotify <https://linux.die.net/man/7/
inotify> that programs can use to monitor file system events.
Note:
On most systems the maximum number of watches that can be created per user is limited to 8192.
watchdog needs one per directory to monitor. To change this limit, edit /etc/sysctl.conf and
add:
fs.inotify.max_user_watches=16384
macOS The Darwin kernel/OS X API maintains two ways to monitor directories for file system events:
• kqueue <https://www.freebsd.org/cgi/man.cgi?query=kqueue&sektion=2>
• FSEvents <https://developer.apple.com/library/mac/#documentation/Darwin/Conceptual/
FSEvents_ProgGuide/Introduction/Introduction.html>
watchdog can use whichever one is available, preferring FSEvents over kqueue(2). kqueue(2) uses
open file descriptors for monitoring and the current implementation uses macOS File System
Monitoring Performance Guidelines <https://developer.apple.com/library/ios/#documentation/
Performance/Conceptual/FileSystem/Articles/TrackingChanges.html> to open these file descriptors
only to monitor events, thus allowing OS X to unmount volumes that are being watched without
locking them.
Note:
More information about how watchdog uses kqueue(2) is noted in BSD Unix variants. Much of this
information applies to macOS as well.
BSD Unix variants
BSD variants come with kqueue <https://www.freebsd.org/cgi/man.cgi?query=kqueue&sektion=2> which
programs can use to monitor changes to open file descriptors. Because of the way kqueue(2) works,
watchdog needs to open these files and directories in read-only non-blocking mode and keep books
about them.
watchdog will automatically open file descriptors for all new files/directories created and close
those for which are deleted.
Note:
The maximum number of open file descriptor per process limit on your operating system can
hinder watchdog's ability to monitor files.
You should ensure this limit is set to at least 1024 (or a value suitable to your usage). The
following command appended to your ~/.profile configuration file does this for you:
ulimit -n 1024
Windows Vista and later
The Windows API provides the ReadDirectoryChangesW <https://docs.microsoft.com/windows/win32/api/
winbase/nf-winbase-readdirectorychangesw>. watchdog currently contains implementation for a
synchronous approach requiring additional API functionality only available in Windows Vista and
later.
Note:
Since renaming is not the same operation as movement on Windows, watchdog tries hard to convert
renames to movement events. Also, because the ReadDirectoryChangesW <https://docs.microsoft
.com/windows/win32/api/winbase/nf-winbase-readdirectorychangesw> API function returns
rename/movement events for directories even before the underlying I/O is complete, watchdog may
not be able to completely scan the moved directory in order to successfully queue movement
events for files and directories within it.
Note:
Since the Windows API does not provide information about whether an object is a file or a
directory, delete events for directories may be reported as a file deleted event.
OS Independent Polling
watchdog also includes a fallback-implementation that polls watched directories for changes by
periodically comparing snapshots of the directory tree.
QUICKSTART
Below we present a simple example that monitors the current directory recursively (which means, it will
traverse any sub-directories) to detect changes. Here is what we will do with the API:
1. Create an instance of the watchdog.observers.Observer <#watchdog.observers.Observer> thread class.
2. Implement a subclass of watchdog.events.FileSystemEventHandler <#watchdog.events
.FileSystemEventHandler>.
3. Schedule monitoring a few paths with the observer instance attaching the event handler.
4. Start the observer thread and wait for it generate events without blocking our main thread.
By default, an watchdog.observers.Observer <#watchdog.observers.Observer> instance will not monitor
sub-directories. By passing recursive=True in the call to watchdog.observers.Observer.schedule()
monitoring entire directory trees is ensured.
A Simple Example
The following example program will monitor the current directory recursively for file system changes and
simply print them to the console:
import time
from watchdog.events import FileSystemEvent, FileSystemEventHandler
from watchdog.observers import Observer
class MyEventHandler(FileSystemEventHandler):
def on_any_event(self, event: FileSystemEvent) -> None:
print(event)
event_handler = MyEventHandler()
observer = Observer()
observer.schedule(event_handler, ".", recursive=True)
observer.start()
try:
while True:
time.sleep(1)
finally:
observer.stop()
observer.join()
To stop the program, press Control-C.
Typing
If you are using type annotations it is important to note that watchdog.observers.Observer <#watchdog
.observers.Observer> is not actually a class; it is a variable that hold the "best" observer class
available on your platform.
In order to correctly type your own code your should use watchdog.observers.api.BaseObserver <#watchdog
.observers.api.BaseObserver>. For example:
from watchdog.observers import Observer
from watchdog.observers.api import BaseObserver
def my_func(obs: BaseObserver) -> None:
# Do something with obs
pass
observer: BaseObserver = Observer()
my_func(observer)
API REFERENCE
watchdog.events
module watchdog.events
synopsis
File system events and event handlers.
author <yesudeep@google.com> (Yesudeep Mangalapilly)
author <contact@tiger-222.fr> (Mickaël Schoentgen)
Event Classes
class watchdog.events.FileSystemEvent(src_path: bytes | str, dest_path: bytes | str = '', is_synthetic:
bool = False)
Bases: object
Immutable type that represents a file system event that is triggered when a change occurs on the
monitored file system.
All FileSystemEvent objects are required to be immutable and hence can be used as keys in
dictionaries or be added to sets.
is_directory: bool = False
True if event was synthesized; False otherwise. These are events that weren't actually
broadcast by the OS, but are presumed to have happened based on other, actual events.
class watchdog.events.FileSystemMovedEvent(src_path: bytes | str, dest_path: bytes | str = '',
is_synthetic: bool = False)
Bases: FileSystemEvent
File system event representing any kind of file system movement.
class watchdog.events.FileMovedEvent(src_path: bytes | str, dest_path: bytes | str = '', is_synthetic:
bool = False)
Bases: FileSystemMovedEvent
File system event representing file movement on the file system.
class watchdog.events.DirMovedEvent(src_path: bytes | str, dest_path: bytes | str = '', is_synthetic:
bool = False)
Bases: FileSystemMovedEvent
File system event representing directory movement on the file system.
is_directory: bool = True
True if event was synthesized; False otherwise. These are events that weren't actually
broadcast by the OS, but are presumed to have happened based on other, actual events.
class watchdog.events.FileModifiedEvent(src_path: bytes | str, dest_path: bytes | str = '', is_synthetic:
bool = False)
Bases: FileSystemEvent
File system event representing file modification on the file system.
class watchdog.events.DirModifiedEvent(src_path: bytes | str, dest_path: bytes | str = '', is_synthetic:
bool = False)
Bases: FileSystemEvent
File system event representing directory modification on the file system.
is_directory: bool = True
True if event was synthesized; False otherwise. These are events that weren't actually
broadcast by the OS, but are presumed to have happened based on other, actual events.
class watchdog.events.FileCreatedEvent(src_path: bytes | str, dest_path: bytes | str = '', is_synthetic:
bool = False)
Bases: FileSystemEvent
File system event representing file creation on the file system.
class watchdog.events.FileClosedEvent(src_path: bytes | str, dest_path: bytes | str = '', is_synthetic:
bool = False)
Bases: FileSystemEvent
File system event representing file close on the file system.
class watchdog.events.FileClosedNoWriteEvent(src_path: bytes | str, dest_path: bytes | str = '',
is_synthetic: bool = False)
Bases: FileSystemEvent
File system event representing an unmodified file close on the file system.
class watchdog.events.FileOpenedEvent(src_path: bytes | str, dest_path: bytes | str = '', is_synthetic:
bool = False)
Bases: FileSystemEvent
File system event representing file close on the file system.
class watchdog.events.DirCreatedEvent(src_path: bytes | str, dest_path: bytes | str = '', is_synthetic:
bool = False)
Bases: FileSystemEvent
File system event representing directory creation on the file system.
is_directory: bool = True
True if event was synthesized; False otherwise. These are events that weren't actually
broadcast by the OS, but are presumed to have happened based on other, actual events.
class watchdog.events.FileDeletedEvent(src_path: bytes | str, dest_path: bytes | str = '', is_synthetic:
bool = False)
Bases: FileSystemEvent
File system event representing file deletion on the file system.
class watchdog.events.DirDeletedEvent(src_path: bytes | str, dest_path: bytes | str = '', is_synthetic:
bool = False)
Bases: FileSystemEvent
File system event representing directory deletion on the file system.
is_directory: bool = True
True if event was synthesized; False otherwise. These are events that weren't actually
broadcast by the OS, but are presumed to have happened based on other, actual events.
Event Handler Classes
class watchdog.events.FileSystemEventHandler
Bases: object
Base file system event handler that you can override methods from.
dispatch(event: FileSystemEvent <#watchdog.events.FileSystemEvent>) -> None
Dispatches events to the appropriate methods.
Parameters
event (FileSystemEvent) -- The event object representing the file system event.
on_any_event(event: FileSystemEvent <#watchdog.events.FileSystemEvent>) -> None
Catch-all event handler.
Parameters
event (FileSystemEvent) -- The event object representing the file system event.
on_closed(event: FileClosedEvent <#watchdog.events.FileClosedEvent>) -> None
Called when a file opened for writing is closed.
Parameters
event (FileClosedEvent) -- Event representing file closing.
on_closed_no_write(event: FileClosedNoWriteEvent <#watchdog.events.FileClosedNoWriteEvent>) ->
None
Called when a file opened for reading is closed.
Parameters
event (FileClosedNoWriteEvent) -- Event representing file closing.
on_created(event: DirCreatedEvent <#watchdog.events.DirCreatedEvent> | FileCreatedEvent <#watchdog
.events.FileCreatedEvent>) -> None
Called when a file or directory is created.
Parameters
event (DirCreatedEvent or FileCreatedEvent) -- Event representing file/directory
creation.
on_deleted(event: DirDeletedEvent <#watchdog.events.DirDeletedEvent> | FileDeletedEvent <#watchdog
.events.FileDeletedEvent>) -> None
Called when a file or directory is deleted.
Parameters
event (DirDeletedEvent or FileDeletedEvent) -- Event representing file/directory
deletion.
on_modified(event: DirModifiedEvent <#watchdog.events.DirModifiedEvent> | FileModifiedEvent <#
watchdog.events.FileModifiedEvent>) -> None
Called when a file or directory is modified.
Parameters
event (DirModifiedEvent or FileModifiedEvent) -- Event representing file/directory
modification.
on_moved(event: DirMovedEvent <#watchdog.events.DirMovedEvent> | FileMovedEvent <#watchdog.events
.FileMovedEvent>) -> None
Called when a file or a directory is moved or renamed.
Parameters
event (DirMovedEvent or FileMovedEvent) -- Event representing file/directory
movement.
on_opened(event: FileOpenedEvent <#watchdog.events.FileOpenedEvent>) -> None
Called when a file is opened.
Parameters
event (FileOpenedEvent) -- Event representing file opening.
class watchdog.events.PatternMatchingEventHandler(*, patterns: list[str] | None = None, ignore_patterns:
list[str] | None = None, ignore_directories: bool = False, case_sensitive: bool = False)
Bases: FileSystemEventHandler
Matches given patterns with file paths associated with occurring events. Uses pathlib's
PurePath.match() method. patterns and ignore_patterns are expected to be a list of strings.
property case_sensitive: bool
(Read-only) True if path names should be matched sensitive to case; False otherwise.
dispatch(event: FileSystemEvent <#watchdog.events.FileSystemEvent>) -> None
Dispatches events to the appropriate methods.
Parameters
event (FileSystemEvent) -- The event object representing the file system event.
property ignore_directories: bool
(Read-only) True if directories should be ignored; False otherwise.
property ignore_patterns: list[str] | None
(Read-only) Patterns to ignore matching event paths.
property patterns: list[str] | None
(Read-only) Patterns to allow matching event paths.
class watchdog.events.RegexMatchingEventHandler(*, regexes: list[str] | None = None, ignore_regexes:
list[str] | None = None, ignore_directories: bool = False, case_sensitive: bool = False)
Bases: FileSystemEventHandler
Matches given regexes with file paths associated with occurring events. Uses the re module.
property case_sensitive: bool
(Read-only) True if path names should be matched sensitive to case; False otherwise.
dispatch(event: FileSystemEvent <#watchdog.events.FileSystemEvent>) -> None
Dispatches events to the appropriate methods.
Parameters
event (FileSystemEvent) -- The event object representing the file system event.
property ignore_directories: bool
(Read-only) True if directories should be ignored; False otherwise.
property ignore_regexes: list[Pattern[str]]
(Read-only) Regexes to ignore matching event paths.
property regexes: list[Pattern[str]]
(Read-only) Regexes to allow matching event paths.
class watchdog.events.LoggingEventHandler(*, logger: Logger | None = None)
Bases: FileSystemEventHandler
Logs all the events captured.
on_closed(event: FileClosedEvent <#watchdog.events.FileClosedEvent>) -> None
Called when a file opened for writing is closed.
Parameters
event (FileClosedEvent) -- Event representing file closing.
on_closed_no_write(event: FileClosedNoWriteEvent <#watchdog.events.FileClosedNoWriteEvent>) ->
None
Called when a file opened for reading is closed.
Parameters
event (FileClosedNoWriteEvent) -- Event representing file closing.
on_created(event: DirCreatedEvent <#watchdog.events.DirCreatedEvent> | FileCreatedEvent <#watchdog
.events.FileCreatedEvent>) -> None
Called when a file or directory is created.
Parameters
event (DirCreatedEvent or FileCreatedEvent) -- Event representing file/directory
creation.
on_deleted(event: DirDeletedEvent <#watchdog.events.DirDeletedEvent> | FileDeletedEvent <#watchdog
.events.FileDeletedEvent>) -> None
Called when a file or directory is deleted.
Parameters
event (DirDeletedEvent or FileDeletedEvent) -- Event representing file/directory
deletion.
on_modified(event: DirModifiedEvent <#watchdog.events.DirModifiedEvent> | FileModifiedEvent <#
watchdog.events.FileModifiedEvent>) -> None
Called when a file or directory is modified.
Parameters
event (DirModifiedEvent or FileModifiedEvent) -- Event representing file/directory
modification.
on_moved(event: DirMovedEvent <#watchdog.events.DirMovedEvent> | FileMovedEvent <#watchdog.events
.FileMovedEvent>) -> None
Called when a file or a directory is moved or renamed.
Parameters
event (DirMovedEvent or FileMovedEvent) -- Event representing file/directory
movement.
on_opened(event: FileOpenedEvent <#watchdog.events.FileOpenedEvent>) -> None
Called when a file is opened.
Parameters
event (FileOpenedEvent) -- Event representing file opening.
watchdog.observers.api
Immutables
class watchdog.observers.api.ObservedWatch(path: str | Path, *, recursive: bool, event_filter:
list[type[FileSystemEvent <#watchdog.events.FileSystemEvent>]] | None = None)
Bases: object
An scheduled watch.
Parameters
• path -- Path string.
• recursive -- True if watch is recursive; False otherwise.
• event_filter -- Optional collection of watchdog.events.FileSystemEvent to watch
property event_filter: frozenset[type[FileSystemEvent <#watchdog.events.FileSystemEvent>]] | None
Collection of event types watched for the path
property is_recursive: bool
Determines whether subdirectories are watched for the path.
property path: str
The path that this watch monitors.
Collections
class watchdog.observers.api.EventQueue(maxsize=0)
Bases: SkipRepeatsQueue
Thread-safe event queue based on a special queue that skips adding the same event
(FileSystemEvent) multiple times consecutively. Thus avoiding dispatching multiple event handling
calls when multiple identical events are produced quicker than an observer can consume them.
Classes
class watchdog.observers.api.EventEmitter(event_queue: EventQueue <#watchdog.observers.api.EventQueue>,
watch: ObservedWatch <#watchdog.observers.api.ObservedWatch>, *, timeout: float = 1.0, event_filter:
list[type[FileSystemEvent <#watchdog.events.FileSystemEvent>]] | None = None)
Bases: BaseThread
Producer thread base class subclassed by event emitters that generate events and populate a queue
with them.
Parameters
• event_queue (watchdog.events.EventQueue) -- The event queue to populate with generated
events.
• watch (ObservedWatch) -- The watch to observe and produce events for.
• timeout (float) -- Timeout (in seconds) between successive attempts at reading events.
• event_filter (Iterable[watchdog.events.FileSystemEvent] | None) -- Collection of event
types to emit, or None for no filtering (default).
queue_event(event: FileSystemEvent <#watchdog.events.FileSystemEvent>) -> None
Queues a single event.
Parameters
event (An instance of watchdog.events.FileSystemEvent or a subclass.) -- Event to be
queued.
queue_events(timeout: float) -> None
Override this method to populate the event queue with events per interval period.
Parameters
timeout (float) -- Timeout (in seconds) between successive attempts at reading
events.
run() -> None
Method representing the thread's activity.
You may override this method in a subclass. The standard run() method invokes the callable
object passed to the object's constructor as the target argument, if any, with sequential
and keyword arguments taken from the args and kwargs arguments, respectively.
property timeout: float
Blocking timeout for reading events.
property watch: ObservedWatch <#watchdog.observers.api.ObservedWatch>
The watch associated with this emitter.
class watchdog.observers.api.EventDispatcher(*, timeout: float = 1.0)
Bases: BaseThread
Consumer thread base class subclassed by event observer threads that dispatch events from an event
queue to appropriate event handlers.
Parameters
timeout (float) -- Timeout value (in seconds) passed to emitters constructions in the child
class BaseObserver.
dispatch_events(event_queue: EventQueue <#watchdog.observers.api.EventQueue>) -> None
Override this method to consume events from an event queue, blocking on the queue for the
specified timeout before raising queue.Empty.
Parameters
event_queue (EventQueue) -- Event queue to populate with one set of events.
Raises queue.Empty
property event_queue: EventQueue <#watchdog.observers.api.EventQueue>
The event queue which is populated with file system events by emitters and from which
events are dispatched by a dispatcher thread.
run() -> None
Method representing the thread's activity.
You may override this method in a subclass. The standard run() method invokes the callable
object passed to the object's constructor as the target argument, if any, with sequential
and keyword arguments taken from the args and kwargs arguments, respectively.
stop() -> None
Signals the thread to stop.
stop_event = <object object>
Event inserted into the queue to signal a requested stop.
property timeout: float
Timeout value to construct emitters with.
class watchdog.observers.api.BaseObserver(emitter_class: type[EventEmitter <#watchdog.observers.api
.EventEmitter>], *, timeout: float = 1.0)
Bases: EventDispatcher
Base observer.
add_handler_for_watch(event_handler: FileSystemEventHandler <#watchdog.events
.FileSystemEventHandler>, watch: ObservedWatch <#watchdog.observers.api.ObservedWatch>) -> None
Adds a handler for the given watch.
Parameters
• event_handler (watchdog.events.FileSystemEventHandler or a subclass) -- An event
handler instance that has appropriate event handling methods which will be called
by the observer in response to file system events.
• watch (An instance of ObservedWatch or a subclass of ObservedWatch) -- The watch
to add a handler for.
dispatch_events(event_queue: EventQueue <#watchdog.observers.api.EventQueue>) -> None
Override this method to consume events from an event queue, blocking on the queue for the
specified timeout before raising queue.Empty.
Parameters
event_queue (EventQueue) -- Event queue to populate with one set of events.
Raises queue.Empty
property emitters: set[EventEmitter <#watchdog.observers.api.EventEmitter>]
Returns event emitter created by this observer.
on_thread_stop() -> None
Override this method instead of stop(). stop() calls this method.
This method is called immediately after the thread is signaled to stop.
remove_handler_for_watch(event_handler: FileSystemEventHandler <#watchdog.events
.FileSystemEventHandler>, watch: ObservedWatch <#watchdog.observers.api.ObservedWatch>) -> None
Removes a handler for the given watch.
Parameters
• event_handler (watchdog.events.FileSystemEventHandler or a subclass) -- An event
handler instance that has appropriate event handling methods which will be called
by the observer in response to file system events.
• watch (An instance of ObservedWatch or a subclass of ObservedWatch) -- The watch
to remove a handler for.
schedule(event_handler: FileSystemEventHandler <#watchdog.events.FileSystemEventHandler>, path:
str, *, recursive: bool = False, event_filter: list[type[FileSystemEvent <#watchdog.events
.FileSystemEvent>]] | None = None) -> ObservedWatch <#watchdog.observers.api.ObservedWatch>
Schedules watching a path and calls appropriate methods specified in the given event
handler in response to file system events.
Parameters
• event_handler (watchdog.events.FileSystemEventHandler or a subclass) -- An event
handler instance that has appropriate event handling methods which will be called
by the observer in response to file system events.
• path (str) -- Directory path that will be monitored.
• recursive (bool) -- True if events will be emitted for sub-directories traversed
recursively; False otherwise.
• event_filter (Iterable[watchdog.events.FileSystemEvent] | None) -- Collection of
event types to emit, or None for no filtering (default).
Returns
An ObservedWatch object instance representing a watch.
start() -> None
Start the thread's activity.
It must be called at most once per thread object. It arranges for the object's run() method
to be invoked in a separate thread of control.
This method will raise a RuntimeError if called more than once on the same thread object.
unschedule(watch: ObservedWatch <#watchdog.observers.api.ObservedWatch>) -> None
Unschedules a watch.
Parameters
watch (An instance of ObservedWatch or a subclass of ObservedWatch) -- The watch to
unschedule.
unschedule_all() -> None
Unschedules all watches and detaches all associated event handlers.
watchdog.observers
module watchdog.observers
synopsis
Observer that picks a native implementation if available.
author <yesudeep@google.com> (Yesudeep Mangalapilly)
author <contact@tiger-222.fr> (Mickaël Schoentgen)
Classes
watchdog.observers.Observer
alias of InotifyObserver
Observer thread that schedules watching directories and dispatches calls to event handlers.
You can also import platform specific classes directly and use it instead of Observer. Here is a list of
implemented observer classes.:
┌───────────────────────────────────────────┬──────────────────────────────┬────────────────────────────┐
│ Class │ Platforms │ Note │
├───────────────────────────────────────────┼──────────────────────────────┼────────────────────────────┤
│ inotify.InotifyObserver │ Linux 2.6.13+ │ inotify(7) based observer │
├───────────────────────────────────────────┼──────────────────────────────┼────────────────────────────┤
│ fsevents.FSEventsObserver │ macOS │ FSEvents based observer │
├───────────────────────────────────────────┼──────────────────────────────┼────────────────────────────┤
│ kqueue.KqueueObserver │ macOS and BSD with kqueue(2) │ kqueue(2) based observer │
├───────────────────────────────────────────┼──────────────────────────────┼────────────────────────────┤
│ read_directory_changes.WindowsApiObserver │ Microsoft Windows │ Windows API-based observer │
├───────────────────────────────────────────┼──────────────────────────────┼────────────────────────────┤
│ polling.PollingObserver │ Any │ fallback implementation │
└───────────────────────────────────────────┴──────────────────────────────┴────────────────────────────┘
watchdog.observers.polling
module watchdog.observers.polling
synopsis
Polling emitter implementation.
author <yesudeep@google.com> (Yesudeep Mangalapilly)
author <contact@tiger-222.fr> (Mickaël Schoentgen)
Classes
class watchdog.observers.polling.PollingObserver(*, timeout: float = 1.0)
Bases: BaseObserver
Platform-independent observer that polls a directory to detect file system changes.
class watchdog.observers.polling.PollingObserverVFS(stat: Callable[[str], os.stat_result], listdir:
Callable[[str | None], Iterator[os.DirEntry]], *, polling_interval: int = 1)
Bases: BaseObserver
File system independent observer that polls a directory to detect changes.
__init__(stat: Callable[[str], os.stat_result], listdir: Callable[[str | None],
Iterator[os.DirEntry]], *, polling_interval: int = 1) -> None
Parameters
• stat -- stat function. See os.stat for details.
• listdir -- listdir function. See os.scandir for details.
• polling_interval (int) -- interval in seconds between polling the file system.
watchdog.utils
module watchdog.utils
synopsis
Utility classes and functions.
author <yesudeep@google.com> (Yesudeep Mangalapilly)
author <contact@tiger-222.fr> (Mickaël Schoentgen)
Classes
class watchdog.utils.BaseThread
Bases: Thread
Convenience class for creating stoppable threads.
property daemon
A boolean value indicating whether this thread is a daemon thread.
This must be set before start() is called, otherwise RuntimeError is raised. Its initial
value is inherited from the creating thread; the main thread is not a daemon thread and
therefore all threads created in the main thread default to daemon = False.
The entire Python program exits when only daemon threads are left.
getName()
Return a string used for identification purposes only.
This method is deprecated, use the name attribute instead.
property ident
Thread identifier of this thread or None if it has not been started.
This is a nonzero integer. See the get_ident() function. Thread identifiers may be recycled
when a thread exits and another thread is created. The identifier is available even after
the thread has exited.
isDaemon()
Return whether this thread is a daemon.
This method is deprecated, use the daemon attribute instead.
is_alive()
Return whether the thread is alive.
This method returns True just before the run() method starts until just after the run()
method terminates. See also the module function enumerate().
join(timeout=None)
Wait until the thread terminates.
This blocks the calling thread until the thread whose join() method is called terminates --
either normally or through an unhandled exception or until the optional timeout occurs.
When the timeout argument is present and not None, it should be a floating-point number
specifying a timeout for the operation in seconds (or fractions thereof). As join() always
returns None, you must call is_alive() after join() to decide whether a timeout happened --
if the thread is still alive, the join() call timed out.
When the timeout argument is not present or None, the operation will block until the thread
terminates.
A thread can be join()ed many times.
join() raises a RuntimeError if an attempt is made to join the current thread as that would
cause a deadlock. It is also an error to join() a thread before it has been started and
attempts to do so raises the same exception.
property name
A string used for identification purposes only.
It has no semantics. Multiple threads may be given the same name. The initial name is set
by the constructor.
property native_id
Native integral thread ID of this thread, or None if it has not been started.
This is a non-negative integer. See the get_native_id() function. This represents the
Thread ID as reported by the kernel.
on_thread_start() -> None
Override this method instead of start(). start() calls this method.
This method is called right before this thread is started and this object's run() method is
invoked.
on_thread_stop() -> None
Override this method instead of stop(). stop() calls this method.
This method is called immediately after the thread is signaled to stop.
run() Method representing the thread's activity.
You may override this method in a subclass. The standard run() method invokes the callable
object passed to the object's constructor as the target argument, if any, with sequential
and keyword arguments taken from the args and kwargs arguments, respectively.
setDaemon(daemonic)
Set whether this thread is a daemon.
This method is deprecated, use the .daemon property instead.
setName(name)
Set the name string for this thread.
This method is deprecated, use the name attribute instead.
should_keep_running() -> bool
Determines whether the thread should continue running.
start() -> None
Start the thread's activity.
It must be called at most once per thread object. It arranges for the object's run() method
to be invoked in a separate thread of control.
This method will raise a RuntimeError if called more than once on the same thread object.
stop() -> None
Signals the thread to stop.
watchdog.utils.dirsnapshot
module watchdog.utils.dirsnapshot
synopsis
Directory snapshots and comparison.
author <yesudeep@google.com> (Yesudeep Mangalapilly)
author <contact@tiger-222.fr> (Mickaël Schoentgen)
Where are the moved events? They 'disappeared'
This implementation does not take partition boundaries into consideration. It will only work
when the directory tree is entirely on the same file system. More specifically, any part of the
code that depends on inode numbers can break if partition boundaries are crossed. In these
cases, the snapshot diff will represent file/directory movement as created and deleted events.
Classes
class watchdog.utils.dirsnapshot.DirectorySnapshot(path: str, *, recursive: bool = True, stat:
Callable[[str], os.stat_result] = <built-in function stat>, listdir: Callable[[str | None],
Iterator[os.DirEntry]] = <built-in function scandir>)
Bases: object
A snapshot of stat information of files in a directory.
Parameters
• path (str) -- The directory path for which a snapshot should be taken.
• recursive (bool) -- True if the entire directory tree should be included in the snapshot;
False otherwise.
• stat --
Use custom stat function that returns a stat structure for path. Currently only st_dev,
st_ino, st_mode and st_mtime are needed.
A function taking a path as argument which will be called for every entry in the
directory tree.
• listdir -- Use custom listdir function. For details see os.scandir.
inode(path: bytes | str) -> tuple[int, int]
Returns an id for path.
path(uid: tuple[int, int]) -> bytes | str | None
Returns path for id. None if id is unknown to this snapshot.
property paths: set[bytes | str]
Set of file/directory paths in the snapshot.
stat_info(path: bytes | str) -> stat_result
Returns a stat information object for the specified path from the snapshot.
Attached information is subject to change. Do not use unless you specify stat in
constructor. Use inode(), mtime(), isdir() instead.
Parameters
path -- The path for which stat information should be obtained from a snapshot.
class watchdog.utils.dirsnapshot.DirectorySnapshotDiff(ref: DirectorySnapshot <#watchdog.utils
.dirsnapshot.DirectorySnapshot>, snapshot: DirectorySnapshot <#watchdog.utils.dirsnapshot
.DirectorySnapshot>, *, ignore_device: bool = False)
Bases: object
Compares two directory snapshots and creates an object that represents the difference between the
two snapshots.
Parameters
• ref (DirectorySnapshot) -- The reference directory snapshot.
• snapshot (DirectorySnapshot) -- The directory snapshot which will be compared with the
reference snapshot.
• ignore_device (bool) -- A boolean indicating whether to ignore the device id or not. By
default, a file may be uniquely identified by a combination of its first inode and its
device id. The problem is that the device id may (or may not) change between system
boots. This problem would cause the DirectorySnapshotDiff to think a file has been
deleted and created again but it would be the exact same file. Set to True only if you
are sure you will always use the same device.
class ContextManager(path: str, *, recursive: bool = True, stat: Callable[[str], os.stat_result] =
<built-in function stat>, listdir: Callable[[str | None], Iterator[os.DirEntry]] = <built-in
function scandir>, ignore_device: bool = False)
Bases: object
Context manager that creates two directory snapshots and a diff object that represents the
difference between the two snapshots.
Parameters
• path (str) -- The directory path for which a snapshot should be taken.
• recursive (bool) -- True if the entire directory tree should be included in the
snapshot; False otherwise.
• stat --
Use custom stat function that returns a stat structure for path. Currently only
st_dev, st_ino, st_mode and st_mtime are needed.
A function taking a path as argument which will be called for every entry in the
directory tree.
• listdir -- Use custom listdir function. For details see os.scandir.
• ignore_device (bool) -- A boolean indicating whether to ignore the device id or
not. By default, a file may be uniquely identified by a combination of its first
inode and its device id. The problem is that the device id may (or may not) change
between system boots. This problem would cause the DirectorySnapshotDiff to think
a file has been deleted and created again but it would be the exact same file.
Set to True only if you are sure you will always use the same device.
property dirs_created: list[bytes | str]
List of directories that were created.
property dirs_deleted: list[bytes | str]
List of directories that were deleted.
property dirs_modified: list[bytes | str]
List of directories that were modified.
property dirs_moved: list[tuple[bytes | str, bytes | str]]
List of directories that were moved.
Each event is a two-tuple the first item of which is the path that has been renamed to the
second item in the tuple.
property files_created: list[bytes | str]
List of files that were created.
property files_deleted: list[bytes | str]
List of files that were deleted.
property files_modified: list[bytes | str]
List of files that were modified.
property files_moved: list[tuple[bytes | str, bytes | str]]
List of files that were moved.
Each event is a two-tuple the first item of which is the path that has been renamed to the
second item in the tuple.
class watchdog.utils.dirsnapshot.EmptyDirectorySnapshot
Bases: DirectorySnapshot
Class to implement an empty snapshot. This is used together with DirectorySnapshot and
DirectorySnapshotDiff in order to get all the files/folders in the directory as created.
static path(_: Any) -> None
Mock up method to return the path of the received inode. As the snapshot is intended to be
empty, it always returns None.
Returns
None.
property paths: set
Mock up method to return a set of file/directory paths in the snapshot. As the snapshot is
intended to be empty, it always returns an empty set.
Returns
An empty set.
watchdog.tricks
module watchdog.tricks
synopsis
Utility event handlers.
author <yesudeep@google.com> (Yesudeep Mangalapilly)
author <contact@tiger-222.fr> (Mickaël Schoentgen)
Classes
class watchdog.tricks.Trick(*, patterns: list[str] | None = None, ignore_patterns: list[str] | None =
None, ignore_directories: bool = False, case_sensitive: bool = False)
Bases: PatternMatchingEventHandler
Your tricks should subclass this class.
class watchdog.tricks.LoggerTrick(*, patterns: list[str] | None = None, ignore_patterns: list[str] | None
= None, ignore_directories: bool = False, case_sensitive: bool = False)
Bases: Trick
A simple trick that does only logs events.
on_any_event(event: FileSystemEvent <#watchdog.events.FileSystemEvent>) -> None
Catch-all event handler.
Parameters
event (FileSystemEvent) -- The event object representing the file system event.
class watchdog.tricks.ShellCommandTrick(shell_command: str, *, patterns: list[str] | None = None,
ignore_patterns: list[str] | None = None, ignore_directories: bool = False, wait_for_process: bool =
False, drop_during_process: bool = False)
Bases: Trick
Executes shell commands in response to matched events.
on_any_event(event: FileSystemEvent <#watchdog.events.FileSystemEvent>) -> None
Catch-all event handler.
Parameters
event (FileSystemEvent) -- The event object representing the file system event.
class watchdog.tricks.AutoRestartTrick(command: list[str], *, patterns: list[str] | None = None,
ignore_patterns: list[str] | None = None, ignore_directories: bool = False, stop_signal: Signals | int =
Signals.SIGINT, kill_after: int = 10, debounce_interval_seconds: int = 0, restart_on_command_exit: bool =
True)
Bases: Trick
Starts a long-running subprocess and restarts it on matched events.
The command parameter is a list of command arguments, such as ['bin/myserver', '-c',
'etc/myconfig.ini'].
Call start() after creating the Trick. Call stop() when stopping the process.
on_any_event(event: FileSystemEvent <#watchdog.events.FileSystemEvent>) -> None
Catch-all event handler.
Parameters
event (FileSystemEvent) -- The event object representing the file system event.
CONTRIBUTING
Welcome hacker! So you have got something you would like to see in watchdog? Whee. This document will
help you get started.
Important URLs
watchdog uses git <https://git-scm.org/> to track code history and hosts its code repository <https://
github.com/gorakhargosh/watchdog> at github <https://github.com/>. The issue tracker <https://github.com/
gorakhargosh/watchdog/issues> is where you can file bug reports and request features or enhancements to
watchdog.
Before you start
Ensure your system has the following programs and libraries installed before beginning to hack:
1. Python <https://python.org>
2. git <https://git-scm.org/>
3. XCode <https://developer.apple.com/technologies/tools/xcode.html> (on macOS)
Setting up the Work Environment
Steps to setting up a clean environment:
1. Fork the code repository <https://github.com/gorakhargosh/watchdog> into your github <https://github
.com/> account.
2. Clone fork and create virtual environment:
$ git clone https://github.com/gorakhargosh/watchdog.git
$ cd watchdog
$ python -m venv venv
3. Linux
$ . venv/bin/activate
(venv)$ python -m pip instal -e '.'
4. Windows
> venv\Scripts\activate
(venv)> python -m pip instal -e '.'
That's it with the setup. Now you're ready to hack on watchdog.
Happy hacking!
Found a bug in or want a feature added to watchdog? You can fork the official code repository <https://
github.com/gorakhargosh/watchdog> or file an issue ticket at the issue tracker <https://github.com/
gorakhargosh/watchdog/issues>. You may also want to refer to Contributing <#hacking> for information
about contributing code or documentation to watchdog.
• Index <>
• Module Index <>
• Search Page <>
Author
Yesudeep Mangalapilly, Mickaël Schoentgen, and contributors
Copyright
2010-2024, Yesudeep Mangalapilly, Mickaël Schoentgen, and contributors
6.0.0 Dec 17, 2025 WATCHDOG(3)